Condensing pressure controls for refrigeration system



Feb. 27, 1968 H. H. HOPKINSON 3,370,438

CONDENSING PRESSURE CONTROLS FOR REFRIGERATION SYSTEM Filed May 4, 1966I5 lo I2 INVENTOR.

HAROLD H. HOPMNSON.

WZWW

ATTORNEY.

United States Patent 337,438 Patented Feh. 27, 1968 Free 3,370,438CQNDENSENG PRESSURE CONTRGLS FOR REFRIGERATION SYSTEM Harold H.Hopkinson, Manlius, N.Y., assiguor to Carrier Corporation, Syracuse,N.Y., a corporation of Delaware Filed May 4, 1966, Ser. No. 547,512 3Claims. (Cl. 62-196) This invention relates to a refrigeration systemand, more particularly, to an arrangement for controlling condensingpressures in a refrigeration system.

To sustain capacity of a refrigeration system, it is essential that anadequate pressure differential be held across the system expansiondevice. Where the system is of the type having an air-cooled condenser,the pressure differential across the expension device is largelydependent upon outdoor temperature conditions. When outdoor temperaturesare low, pressures within the condenser fall while the condensing rateincreases, and the pressure differential across the expansion devicedrops.

To offset the increased condensing rate, such as occurs in air cooledcondensers at low outdoor temperatures, portions of the condenser may beisolated from the system. However, refrigerant as well as oil may betrapped in the separated or isolated portions of the condenser which canreduce system elficiency and cause over-heating of the compressor.

It is a principal object of the present invention to provide a new andimproved refrigeration system.

It is a further object of the present invention to provide an arragementfor controlling head pressure in a refrigeration system by isolatingportions of the system condenser without concurrent trapping ofrefrigerant and lubricant.

It is a further object of the present invention to provide an improvedhead pressure control for refrigeration systems incorporating means toreturn to the system refrigerant and lubricant in those parts of thecondenser separated from the system.

It is an object of the present invention to provide a refrigerationsystem employing alternately usable condensers incorporating means toinsure return of refrigerant and lubricant trapped in the d condenser tothe system.

This invention relates to a refrigeration system comprising incombination, a compressor with suction and discharge sides; refrigerantexpansion means; and evaporator series-connected between the expansionmeans and the suction side of the compressor; condenser means arrangedbetween the discharge side of the compressor and the refrigerantexpansion means, the condenser means including at least two coilsections circuited to provide parallel refrigerant flow paths; firstvalve means between at least one of the condenser coil sections and thedischarge side of the compressor effective when actuated to interruptflow of refrigerant from the compressor to the one coil section; aconduit for returning refrigerant and lubricant trapped in the onecondenser coil section to the system, the conduit communicating with thesystem downstream of the refrigerant expansion means, and including arestricted portion to control the flow of returning refrigerant andlubricant from the one condenser coil section to the system; and secondvalve means for preventing flow of refrigerant from the other of thecondenser coil sections into the one condenser coil section.

Other objects of the invention will be perceived from the ensuingdescription and drawings in which:

FIGURE 1 is a schematic view showing a refrigeration system with headpressure control incorporating the refrigerant and lubricant returnarrangement of the present invention, and

FIGURE 2 is a schematic view of a modified refrigeration system having apluraiity of alternating usable condeners incorporating the refrigerantand lubricant return means of the present invention,

Referring to FIGURE 1 of the drawings, refrigeration system 10 includesoutdoor coil or condenser 12 series connected with the discharge side ofa suitable refrigerant compression means 14 by line 15. In the exemplaryarrangement of FIGURE 1, condenser 12 is comprised of coil sections 16,17, 18 providing parallel paths to refrigerant flow. Coil sections 17,18 are connected to refrigerant line 15 through control valves 20, 21,which may be conveniently operated by solenoids 2t), 21 respectively.Whiie condenser 12 is illustrated as comprising three separate andindividual coil sections, 16, 17, 18, it is understood that the numberof coil sections may be varied to suit individual applications.

Check valves 26, 27 series connect coil sections 17, 18

espectively with refrigerant line 29 and a suitable refrigerantexpansion device such as thermal valve 30. Check valves 26, 27 permitflow of refrigerant from condenser coil sections 17, 18 to valve whilepreventing opposite flow of refrigerant from coil section 16 and line 29into coil sections 17, 13 as will be more apparent hereinafter.

While the refrigerant expansion device is illustrated as comprising athermal expansion valve 30, other suitable expansion devices such as acapillary tube may be contemplated.

Refrigerant line 32 connects expansion valve 3t) with indoor coil orevaporator 35. Refri erant line connects the outlet side of evaporator35 to the suction side of compressor 14 to complete the refrigerationsystem 10.

Refrigerant bypass or drain lines 40, 41connect the outlet side ofcondenser coil sections 17, 18 upstream of check valves 26, 27 withrefrigerant line 32 downstream of expansion valve 36. Drain lines 4%),41 each include a restricted part such as capillary section 43, 44respectively. Capillary sections 43, 44 permit the controlled egress ofliquid refrigerant and lubricant from condenser sections 1", 18 to thesystem.

With control valves 2t 21, relatively hot, high pressure refrigerantfrom compressor 14 passes via line 15 into coil sections 111, 17, 18 ofcondenser 12 Where the refrigerant is condensed. Liquid refrigerant fromcoil sections 16, 17, 1S flows through line 29 to expansion valve 39.Relatively low pressure liquid refrigerant from expansion valve 30passes through line 32 to evaporator coil 35 wherein the liquidrefrigerant is vaporized. Vaporized refrigerant from evaporator 35returns through line 36 to the suction side of compressor 14. Arelatively small amount of liquid refrigerant in condenser coil sections17, 18 may flow through drain lines 4%, 41 and capillary sections .3, 44thereof into line 32 and the system bypassing expansiou valve 3%.

On an increase in system condensing rate, as for example, when outdoorambient temperatures become low, solenoid 21 may be energized from asuitable power source (not shown) to close control valve 21 andinterrupt the flow of refrigerant to condenser coil section 18. it isunderstood that condenser coil sections 16, 17 continue to function inthe usual manner. With closure of valve 21, pressure in condenser coilsection 18 soon approximates the pressure downstream of expansion valve39, that is, system low side pressure. As pressure in coil section 18decreases, coil section 18 in effect functions as an evaporator, andrefrigerant and lubricant trapped therewithin by closure of valve 21returns through line 41 and capillary section 44 to the system. Checkvalve 27 effectively prevents flow of refrigerant from condensersections 16, 17 into condenser section 18. Refrigerant which leaks pastvalve 27 into condenser sec tion 18 returns through line 41 andcapillary 44 into line It is understood that a further reduction incondenser capacity may be effected by energizing solenoid 26' to closecontrol valve 29 and interrupt fiow of refrigerant into condensersection 17.-Check valve 26 prevents ingress of refrigerant from section16 into condenser section 17 while line permits refrigerant andlubricant trapped in condenser section 17 to return to the system.

Check valves in drain lines 40, 41 obviate reverse flow of refrigerantfrom evaporator 35 to condenser section 17 and/or 18 when control valves20 and/ or 21 are closed.

Referring to FIGURE 2 of the drawings, there is shown a refrigerationsystem 49 arranged to permit selective use of either air-cooledcondenser or liquid-cooled condenser 56. Referring thereto, refrigerantline 5% connects the discharge side of a suitable refrigerant compression means 52 through control valves 53, 54 with condensers 55, 56respectively. Valves 59, 60 connect condensers 55, 56 respectively withrefrigerant line 62 and a suitable refrigerant expansion device such asthermal valve 63. Line 64 connects expansion valve 63 with the systemevaporator coil 65. Refrigerant line 68 connects evaporator coil withthe suction side of compression means 52 to complete the refrigerationsystem 49.

Drain lines 70, 71 each with a capillary type restrictor 72, 73respectively, communicate the outlet side of condensers 55, 56 upstreamof control valves 59, 60 with refrigerant line 64. While condensers 55,56 are illustrated as being air and liquid cooled types of condensersrespectively, it is appreciated that condensers 55, 56 both may beeither air or liquid cooled.

When air-cooled condenser 55 is functioning, valves 54, 60 are closedisolating the liquid-cooled condenser 56 through line and capillary 72thereof into the refrigeration system.

While I have described a preferred embodiment of my invention, it willbe understood that my invention is not limited thereto since it may beotherwise embodied Within the scope of the following claims.

I claim:

1. In a refrigeration system including a compressor with suction anddischarge sides, refrigerant expansion means, and an evaporatorseries-connected between said expansion means and the suction side ofsaid compressor, the combination of: condenser means arranged betweenthe discharge side of said compressor and said refrigerant expansionmeans, said condenser means including at least two coil sectionscircuited to provide parallel refrigerant flow paths; first valve meansbetween at least one of said condenser coil sections and the dischargeside of said compressor effective when actuated to interrupt fiow ofrefrigerant from said compressor to said one coil section; a conduit forreturning refrigerant and lubricant trapped in said one condenser coilsection to said system, said conduit communicating with said systemdownstream of said refrigerant expansion means, and including arestricted portion to control the flow of returning refrigerant andlubricant from said one condenser coil section to said system; andsecond valve means for preventing flow of refrigerant from the other ofsaid condenser coil sections into said one condenser coil section.

2. A refrigeration system according to claim 1 including third valvemeans for preventing reverse flow of refrigerant from said systemthrough said conduit into said one condenser coil section.

3. A refrigeration. system according to claim 1 in which said conduitrestricted portion comprises a capillary.

References Cited UNITED STATES PATENTS 2,933,904 4/ 1960 Wellman 62-196XR 3,010,289 11/1961 Kuklinski 6'2l96 3,111,815 11/1963 Roberts 62--196XR MEYER PERLIN, Primary Examiner.

1. IN A REFRIGERATION SYSTEM INCLUDING A COMPRESSOR WITH SUCTION ANDDISCHARGE SIDES, REFRIGERANT EXPANSION MEANS, AND AN EVAPORATORSERIES-CONNECTED BETWEEN SAID EXPANSION MEANS AND THE SUCTION SIDE OFSAID COMPRESSOR, THE COMBINATION OF : CONDENSER MEANS ARRANGED BETWEENTHE DISCHARGE SIDE OF SAID COMPRESSOR AND SAID REFRIGERANT EXPANSIONMEANS, SAID CONDENSER MEANS INCLUDING AT LEAST TWO COIL SECTIONSCIRCUITED TO PROVIDE PARALLEL REFRIGERANT FLOW PATHS; FIRST VALVE MEANSBETWEEN AT LEAST ONE OF SAID CONDENSER COIL SECTIONS AND THE DISCHARGESIDE OF SIDE COMPRESSOR EFFECTIVE WHEN ACTUATED TO INTERRUPT FLOW OFREFRIGERANT FROM SAID COMPRESSOR TO SAID ONE COIL SECTION; A CONDUIT FORRETURNING REFRIGERANT AND LUBRICANT TRAPPED IN SAID ONE CONDENSER COILSECTION TO SAID SYSTEM, SAID CONDUIT COMMUNICATING WITH SAID SYSTEMDOWNSTREAM OF SAID REFRIGERANT EXPANSION MEANS, AND INCLUDING ARESTRICTED PORTION TO CONTROL THE FLOW OF RETURNING REFRIGERANT ANDLUBRICANT FROM SAID ONE CONDENSER COIL SECTION TO SAID SYSTEM; ANDSECOND VALVE MEANS FOR PREVENTING FLOW OF REFRIGERANT FROM THE OTHER OFSAID CONDENSER COIL SECTIONS INTO SAID ONE CONDENSER SECTION.